The liquid present in the mouth and secreted by the salivary glands. The DNA in such bands is either denser (GC-rich) or less dense (AT-rich) than the DNA in the main band. The second is the secondary spermatocyte, which is produced from the primary spermatocyte by division. A mature male haploid gamete capable of active movement by means of a undulipodium. The genus of birds comprised of the banded penguins. The column of nervous tissue that in vertebrates runs along the back, and that in bony animals is enclosed within the vertebral column. splice sites Locations where RNA splices exons together to form a continuous gene transcript. spore (1) in a plant or fungus, an asexual reproductive cell that does not participate in fertilization; (2) in prokaryotes, a dormant, relatively impervious cell that is resistant to destruction by heating. A new type of organism arising in a single generation. saliva (common names: spit, spittle) /sə-LIE-və/ n. Its capacity for contraction is the essential trait that makes muscles work. Any fraction of DNA that forms a separate band from the main body of DNA during isopycnic Cs CL gradient centrifugation ("satellite" refers to the subordinate or minor status of such bands). Certain aspects of their worldview, based on religious dogmas, have carried over into modern biological thought, for example, their ideas concerning continuity, gradualism, and ideal forms. The outermost coat of the eyeball, extending from the optic nerve to the edges of the cornea. The first of these two types is the primary spermatocyte, which is a mature sex cell that develops from the spermatogonium without division. During spermatogenesis, one of the primordial, undifferentiated sex cells that give rise, via maturation and growth, first to a primary spermatocyte, then via division, to two secondary spermatocytes that in turn divide to form four spermatids, which then mature without further division into four fully functional spermatozoa — spermatogonial /sperm-awd-ə-GŌ-nee-əl/ spermatozoon (pl spermatozoa) /sper-mat-ə-ZŌ-ən; pl: -ZŌ-ə/ n. An angular bend in the large intestine between the transverse and descending colons.

During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, and cognitive performance, and play a large role in the function of the endocrine and immune systems.

The drive to sleep is much less during the day so it is more difficult for infants who do not fall asleep on their own to make it through a sleep cycle transition.

These infants have a partial waking and realize the conditions under which they fell asleep (nursing to sleep, bottle to sleep, pacifier, being held, whatever it is) are not present and then they fully wake up.

saccule /SACK-yool/ (1) a small sac; (2) the lesser of two sacs within the vestibule of the inner ear. salpinx (pl salpinges) /SAL-pinks, sal-PIN-jeez/ n. saltation (also saltatory evolution) /sawl-TAY-shən/ n. The production of new types of organisms via rapid, discontinuous processes; used in opposition to the term gradualism. A human spermatozoon is about 0.005 mm (0.002 in) in length. A ring of muscle controlling passage of an orifice. A developmental defect characterized by failure of fusion of vertebral arches, with or without protrusion and dysplasia of the spinal cord or its membranes. Three spirochete genera, Borrelia, Leptospira, and Treponema, contain organisms that are important causative agents of human disease spiroscope /SPIGH-rō-skope/ n. The name is derived from the Latin term lusus naturae, "sport of nature," which expressed the idea that nature was in some way play a game and entertaining itself when it made new organisms in this way.

Saliva contains enzymes that begin the digestive process. salt Sodium chloride (Na Cl); more broadly, any chemical compound composed of a positive ion other than hydrogen, and a negative ion, other than the hydroxyl group. A biologist who believes evolution is a saltatory process. Generally, satellite DNA appears as separate bands because each band contains many copies of a specific highly repetitive sequence with a specific density due to its particular GC-to-AT ratio. During spermatogenesis, spermatozoa form in huge quantities within the seminiferous tubules of the testes. It has an oval, flattened head containing a haploid nucleus. MORE INFORMATION | PICTURE sphincter /SFING-ter/ n. In humans, it gives rise to all the nerves of the trunk and limbs. The prominence at the posterior extremity of a vertebra. A genus of helical microorganism belonging to the family Pseudomonadacea (Spirillum minus is the causative agent of rat-bite fever). Any member of Spirochaetes, a phylum of helical bacteria. splicing The process of joining adjacent exons after the removal of an intervening intron. Inflammation of, and resulting damage to, the vertebrae. A supposed process — that has never actually been observed — in which living things arise from nonliving matter. The term is usually applied to plants, but sometimes, especially in older literature, also to animals (for example, Darwin called the Ancon sheep a sport). Ejected saliva mixed with mucous and sometimes pus. The most diverse order of Class Reptilia; includes the lizards, snakes, and worm lizards. (1) (also: squamate) scale-covered, scaly; (2) scale-like (as in the cells of squamous epithelial tissue); (3) (also: squama) the anterior portion of either temporal bones in humans and many other mammals (PICTURE 1 | PICTURE 2).